The connectors concerned are used particularly for transmitting signals and electric current between circuit boards or generally in applications which require fast data transmission and/or high signal frequency.
Connectors are attached to a circuit board by the ‘Pin-in Paste’ method where paste is spread onto the circuit board and then the connector is positioned on the circuit board. The circuit board and its connectors and other components are put in a convection oven or in a similar heated and closed section of the assembly line. The circuit boards and the components thereon are heated by actively circulating hot air around the components and the circuit board. Thermal energy solders the contact pins of the connector to the circuit board.
It is known to assemble a connector from wafers which are typically produced by injection-moulding a plastic body around the contact pins of contacts arranged in one row one on top of another. A necessary number of contact pieces are assembled next to one another in the connector at hand, after which the contacts are placed inside the connector body. Wafers facilitate handling of small contacts, keep contacts pins at a correct distance from one another and also support one another.
Soldering of connectors and contact pieces of the prior art to a circuit board involves the following problems: the bodies of wafers attached next to one another limit access of hot air to the lowest contact pins of the wafer. In that case the temperature of the lowest contact pins and the surfaces to be soldered to the pins is lower than that of the other surfaces to be soldered and thus their soldering is unreliable. This is naturally a problem in respect of the reliability of the connector. On the other hand, quick attachment of a connector at as low a temperature as possible is desirable so that the heat does not damage the other components of the circuit board.